Femoral prosthesis with medialized patellar groove

ABSTRACT

A prosthetic femoral component ( 10 ) for an orthopaedic prosthesis has a canted patellar groove adapted for optimal patella/component interaction, with the component configured to have a medial or lateral cant depending upon the method of implantation. The femoral component defines a distal “component transverse plane,” which is a plane tangent to the distal-most points of the component condyles ( 12,14 ). In a “mechanical” implantation, the component transverse plane is substantially normal to the mechanical femoral axis of the femur after the component has been implanted. Where the femoral component is configured to be “mechanically oriented” in this manner, the component has a medially canted patellar groove. On the other hand, an “anatomic” implantation is one in which, after the component has been implanted, the component transverse plane is substantially parallel to an “anatomic” transverse plane. The anatomic transverse plane is perpendicular to the anatomic axis of the femur from a sagittal view, and is inclusive of a line connecting the distal-most points of the natural femoral condyles before resection. Where the femoral component is configured to be “anatomically oriented” in this way, the component has a non-canted or slightly laterally canted patellar groove.

RELATED APPLICATION

This patent application is a U.S. National Stage Filing under 35 U.S.C.§371 of International Patent Application Serial No. PCT/EP2011/004556,filed on Sep. 9, 2011 and published on Mar. 15, 2012 as WO 2012/031774A1, which claims the benefit of priority of U.S. Provisional PatentApplication Ser. No. 61/381,803, filed on Sep. 10, 2010, the benefit ofpriority of each of which is claimed hereby and each of which isincorporated by reference herein in its entirety.

BACKGROUND

1. Technical Field

The present disclosure relates to orthopaedic prostheses and, moreparticularly, to femoral prosthetic components with enhancedpatello-femoral articulation characteristics.

2. Description of the Related Art

Orthopaedic prostheses are commonly utilized to repair and/or replacedamaged bone and tissue in the human body. For example, a kneeprosthesis may include a femoral component which replaces the articularsurface of one or both of the natural femoral condyles, and/or thenatural femoral sulcus. The femoral sulcus (also referred to as apatellar or trochlear groove) articulates with the patella duringflexion and extension of the knee.

In some partial knee arthroplasty (PKA) procedures, natural bone mayonly be resected in the area of the patellar groove, and a prostheticfemoral sulcus component may be inserted in place of the resected bonefor articulation with a natural or prosthetic patella. In a total kneearthroplasty (TKA) procedure, anterior, distal, and posterior portionsof the natural femur are resected. A knee prosthesis including distaland posterior condyles, joined together by an anterior patellar flange,is then installed in place of the resected bone. In a TKA procedure, thepatellar flange includes a prosthetic patellar groove.

A common goal of PKA and TKA procedures is to reproduce natural kneekinematics using the associated prosthetic components and, moregenerally, to produce kinematic characteristics of the knee prosthesisthat promote favorable patient outcomes including minimized pain,enhanced biomechanical efficiency, reproduction of intact kneePatello-Femoral (PF) and Tibio-Femoral (TF) kinematics, short recoverytimes, decreased risk of joint subluxation, and long prostheticcomponent surface lives. To these ends, substantial design efforts havefocused on providing prosthetic components which account for differencesin natural bone structure and joint kinematics among various patientgroups, such as gender, ethnicity, patient size, and the like. Otherconsiderations which figure into the design and function of prostheticknee components include balancing of soft tissue (i.e., ligaments,tendons and the like) near the prosthetic components, specialarticulation characteristics of the knee such as internal/externalrotation and femoral lateral rollback, and hyperextension and deepflexion considerations, for example.

Design efforts have included producing “asymmetric” femoral componentsfor knee prostheses, in which a particular asymmetry of the componentseeks to provide enhanced articular PF and TF characteristics. Withrespect to a patellar groove of such asymmetric components, a grooveangled laterally upward with respect to a femoral mid-plane axis haspreviously been employed.

SUMMARY

The present disclosure provides an alternative prosthetic femoralcomponent for an orthopaedic prosthesis with a canted patellar grooveadapted for optimal patella/component interaction, in which thecomponent is configurable with a medial or lateral cant depending uponthe method of implantation.

The femoral component defines a distal “component transverse plane,”which is a plane tangent to the distal-most points of the componentcondyles.

In a “mechanical” implantation, the component transverse plane issubstantially normal to the mechanical femoral axis of the femur afterthe component has been implanted. Where the femoral component isconfigured to be “mechanically oriented” in this manner, the componenthas a medially canted patellar groove.

On the other hand, an “anatomic” implantation is one in which, after thecomponent has been implanted, the component transverse plane issubstantially parallel to an “anatomic” transverse plane. The anatomictransverse plane is perpendicular to the anatomic axis of the femur froma sagittal view, and is inclusive of a line connecting the distal-mostpoints of the natural femoral condyles before resection. Where thefemoral component is configured to be “anatomically oriented” in thisway, the component has a non-canted or slightly laterally cantedpatellar groove.

The term “perpendicular,” as used herein to describe the relationshipbetween a plane and a line or axis, implies only a two-dimensionalrelationship in which the line forms a right angle to the plane from aparticular perspective. Thus, an axis may be perpendicular to a plane inone perspective (i.e. as viewed when facing a sagittal plane), but maybe angled from another perspective (i.e., as viewed when facing acoronal plane). In contrast, the term “normal,” as used herein todescribe the relationship between a plane and a line or axis, implies athree-dimensional relationship in which the line forms a right angle tothe plane from all perspectives.

The present disclosure is based on the general concept of orienting thepatellar groove of the femoral component such that a reproduction of thenatural femur morphology as well as of the natural knee PF and TFkinematics is sought, and that at the same time the implantation method,i.e. “mechanical” or “anatomic”, is taken into account. Specifically,the implantation method-dependent orientation of the patellar grooveaccording to the present disclosure aligns the femoral componentadvantageously with the femoral head of the femur. In particular, apatellar axis (as defined below) may be approximately oriented such thatthe patellar axis lies in a plane which goes through the femoral head,in particular thereby at least approximately intersecting the geometriccenter of the femoral head. Stated another way, the patellar axis “aims”or “points” toward the center of the femoral head. In order to achievethis aim, the orientation of the patellar groove, and in particular thecant of a suitably defined patellar axis, may be chosen depending on therespective method of implantation.

In use, a component having a patellar axis adapted to point toward thecenter of femoral head 7 is implanted upon an appropriately resectedsurface, in which the choice of component and the choice of resectiontechnique cooperate to ensure that the patellar axis will be properlyoriented (e.g., within plus-or-minus 2 to 3 degrees) toward the centerof head 7. To find the center of femoral head 7, the surgeon may movethe patient's leg through a wide range of motion, while palpating thefemoral head through the skin. Based on the detected movement of femoralhead 7, the surgeon can estimate the size and location of femoral head 7and therefore can estimate the location of the center of femoral head 7.Alternatively, a surgeon may use pre-operative imagine (discussed above)to visually estimate the location of the center of femoral head 7.

By providing a femoral component made in accordance with the presentdisclosure and implanting such femoral component as described herein, itis possible for the first time for such femoral components to compensatefor the effect of the so-called “external rotation” of the femur(external rotation being a phenomenon that is well-known in the art).More particularly, the patellar groove of a femoral component may beoriented with respect to the femoral head, taking into account theimplantation method intended for that femoral component, such that thefemoral component accommodates the “external rotation” of the femur.Advantageously, this accommodation promotes natural PF and TF kneekinematics.

In the illustrated embodiments of the disclosure, the varus/valgusangle, or “knee inclination” measured in a coronal plane, is taken to beequal to the internal/external rotation angle of the knee, as measuredin a transverse plane. Moreover, the femoral prosthesis and associatedbone resections may cooperate to preserve this angular equalitythroughout the range of flexion, such that the femoral componentpromotes balanced ligament tension throughout the range of motion.

In one form thereof, the present invention provides a femoral componentadapted to mount to a femur, the femur defining a mechanical axis and ananatomic axis, the component having a bone-contacting surface and anopposed articulation surface, the component further having proximal,distal, anterior and posterior portions, the component comprising: apair of condyles including a medial condyle and a lateral condyle, eachof the condyles defining respective distal-most points andposterior-most points; a patellar groove proximate the anterior portionof the component; a transverse plane tangent to each of the distal-mostpoints of the condyles; a coronal plane perpendicular to the transverseplane and tangent to at least one of the posterior-most points of thecondyles; a sagittal plane perpendicular to the transverse plane anddisposed between the lateral condyle and the medial condyle, thesagittal plane inclusive of a distal-most point of the patellar groove,the sagittal plane including a component midline that is normal to thetransverse plane and inclusive of the distal-most point of the patellargroove, the patellar groove defining a medially canted patellar axiswhen viewed from an anterior side of the component, the patellar axismedially diverging from the component midline as the patellar axisextends proximally to define a medially canted angle between thepatellar axis and the component midline.

In another form thereof, the present invention provides a femoralcomponent adapted to mount to a femur, the femur having a mechanicalaxis, an anatomic axis and medial and lateral condyles definingdistal-most points, an anatomic transverse plane tangent to thedistal-most points of the medial and lateral condyles of the femur, thecomponent having a bone-contacting surface and an opposed articulationsurface, the component comprising: a pair of condyles including a medialcondyle and a lateral condyle, each of the condyles defining respectivedistal-most points when the component is mounted to the femur, thecondyles further defining respective posterior-most points when thecomponent is mounted to the femur; a transverse plane inclusive of aline connecting the distal-most points of the condyles, the transverseplane oriented to be parallel with the anatomic transverse plane whenthe component is mounted to the femur; a coronal plane perpendicular tothe transverse plane and tangent to at least one of the posterior-mostpoints of the condyles; a sagittal plane perpendicular to the transverseplane and bisecting the component, the sagittal plane defining acomponent midline in the coronal plane, the component midlineequidistant from a lateral edge of the lateral condyle and a medial edgeof the medial condyle; and a patellar groove defining a laterally cantedpatellar axis when viewed from an anterior side of the component,wherein the patellar axis laterally diverges from the component midlineas the patellar axis extends proximally to define a laterally cantedangle between the patellar axis and the component midline, the laterallycanted angle between about zero degrees and about 4 degrees.

In yet another form thereof, the present invention provides a set offemoral components adapted to mount to a femur having an anatomic axisand a mechanical axis, the femur having lateral and medial condyles withrespective distal-most points before resection, the femur defining amechanical transverse plane normal to the mechanical axis and ananatomic transverse plane tangent to each of the distal-most points, theset comprising: a first femoral component having a first lateralcondyle, a first medial condyle opposite the first lateral condyle, suchthat a path from the first lateral condyle toward the first medialcondyle defines a medial direction, and a first anterior flange joiningthe first lateral condyle to the first medial condyle, the firstanterior flange defining a medially canted patellar groove extending inthe medial direction as the medially canted patellar groove extendsproximally; and a second femoral component having a second lateralcondyle, a second medial condyle opposite the second lateral condyle,such that a path from the second medial condyle toward the secondlateral condyle defines a lateral direction, and a second anteriorflange joining the second lateral condyle to the second medial condyle,the second anterior flange defining a laterally canted patellar grooveextending in the lateral direction as the laterally canted patellargroove extends proximally.

In still another form thereof, the present invention provides a femoralcomponent adapted to be mounted to a femur according to a mechanicalimplantation method or according to an anatomic implantation method, thefemur defining a mechanical axis and an anatomic axis, the componenthaving a bone-contacting surface and an opposed articulation surface,the component further having proximal, distal, anterior and posteriorportions, the component comprising: a pair of condyles including amedial condyle and a lateral condyle, each of the condyles definingrespective distal-most points and posterior-most points; a patellargroove proximate the anterior portion of the component; a transverseplane tangent to each of the distal-most points of the condyles; acoronal plane perpendicular to the transverse plane and tangent to atleast one of the posterior-most points of the condyles; a sagittal planeperpendicular to the transverse plane and disposed between the lateralcondyle and the medial condyle, the sagittal plane inclusive of adistal-most point of the patellar groove, the sagittal plane including acomponent midline that is normal to the transverse plane and inclusiveof the distal-most point of the patellar groove, the patellar groovedefining a medially canted patellar axis when viewed from an anteriorside of the component, the patellar axis medially diverging from thecomponent midline as the patellar axis extends proximally to define amedially canted angle between the patellar axis and the componentmidline, or the patellar groove defining a laterally canted patellaraxis when viewed from an anterior side of the component, the patellaraxis laterally diverging from the component midline as the patellar axisextends proximally to define a laterally canted angle between thepatellar axis and the component midline, the medially or laterallycanted patellar axis lying in a plane which intersects a femoral head ofthe femur, in particular which approximately intersects a center of thefemoral head of the femur, when the femoral component is properlymounted to the femur according to the mechanical implantation method orthe anatomic implantation method, respectively.

In yet another form thereof, the present invention provides a method ofimplanting a femoral component onto a distal end of a femur, the methodcomprising: determining the location of a center of a femoral head ofthe femur; resecting the distal end of the femur to create a resecteddistal surface; providing a femoral component comprising a patellargroove proximate an anterior portion of the component, the patellargroove defining a patellar axis when viewed from an anterior side of thecomponent; and implanting the femoral component onto the resected distalsurface such that the patellar axis is oriented toward the center of thefemoral head, such that the patellar axis substantially intersects thecenter of the femoral head.

In yet another form thereof, the present invention provides a method ofimplanting a femoral component onto a distal end of a femur, the methodcomprising: determining the alignment and orientation of a mechanicalaxis of the femur; providing a femoral component, the componentcomprising: a pair of condyles including a medial condyle and a lateralcondyle each defining respective distal-most points; a patellar grooveproximate an anterior portion of the component, the patellar groovedefining a patellar axis as viewed from an anterior side of thecomponent; and implanting the femoral component such that the patellaraxis defines a medially canted angle between the patellar axis and themechanical axis, as projected onto a coronal plane.

In still another form thereof, the present invention provides a methodof implanting a femoral component onto a distal end of a femur, themethod comprising: determining the alignment and orientation of ananatomical axis of the femur; locating the distal-most points ofanatomic femoral condyles of the femur; identifying an anatomictransverse plane that is i) perpendicular to the anatomical axis of thefemur from a sagittal view and ii) inclusive of a line connecting thedistal-most points of the anatomic femoral condyles; providing a femoralcomponent, the component comprising: a pair of condyles including amedial condyle and a lateral condyle each defining respectivedistal-most points; a patellar groove proximate an anterior portion ofthe component, the patellar groove defining a patellar axis as viewedfrom an anterior side of the component; and implanting the femoralcomponent such that the patellar axis forms a laterally canted anglewith respect to a line normal to the anatomic transverse plane, asprojected onto a coronal plane.

BRIEF DESCRIPTION OF THE DRAWINGS

The above mentioned and other features and advantages of this invention,and the manner of attaining them, will become more apparent and theinvention itself will be better understood by reference to the followingdescription of embodiments of the invention taken in conjunction withthe accompanying drawings, wherein:

FIG. 1 is a perspective view of a femoral component in accordance withthe present disclosure, illustrating the planes of an implant coordinatesystem;

FIG. 2 is a side elevation view of the femoral component shown in FIG.1, illustrating a trochlear groove projected in a sagittal plane to forma patellar curve;

FIG. 3 is a front elevation view of a femoral component adapted to bealigned with a mechanical transverse plane in accordance with thepresent disclosure;

FIG. 4 is a front elevation view of a femoral component adapted to bealigned with an anatomic transverse plane in accordance with the presentdisclosure;

FIG. 5 is an elevation view of a femur, illustrating mechanical andanatomic transverse planes in accordance with the present disclosure;

FIG. 6A is an elevation view of a femur with an attached femoralcomponent, with the femur in an extension position; and

FIG. 6B is an elevation view of the femur and femoral component of FIG.6A, with the femur in a flexion position.

Corresponding reference characters indicate corresponding partsthroughout the several views. The exemplifications set out hereinillustrate exemplary embodiments of the invention, and suchexemplifications are not to be construed as limiting the scope of theinvention in any manner.

DETAILED DESCRIPTION

1. Introduction

The present disclosure provides a prosthetic femoral component for usein an orthopaedic knee prosthesis. The prosthetic femoral componentdefines a transverse plane tangent to the distal-most points of theprosthesis condyles, referred to herein as the “component transverseplane.” The component may be implanted in a “mechanical orientation,” inwhich the component transverse plane is substantially parallel to aplane normal to the mechanical axis of the femur, referred to herein asthe “mechanical transverse plane.” Femoral components mounted in amechanical orientation include medially canted patellar grooves, suchthat the patellar groove diverges medially from a midline bisecting thecomponent as the groove extends proximally.

Alternatively, the component may be implanted in an “anatomicalorientation,” in which the component transverse plane is substantiallyparallel to an anteroposterior plane contacting both distal-most pointsof the natural femoral condyles, referred to herein as the “anatomictransverse plane.” Femoral components mounted in an anatomic orientationinclude either i) laterally canted patellar grooves, such that thepatellar groove diverges laterally from a midline bisecting thecomponent as the groove extends proximally, or ii) non-canted grooves,such that the patellar groove does not diverge either medially orlaterally from the midline of the component.

In addition to the medial or lateral cant of the patellar groove, thegroove may also be “shifted” medially or laterally, as described indetail below. More particularly, the point of intersection of theprojection of the patellar groove in a coronal plane (referred to hereinas the “patellar axis,” as discussed below) with the componenttransverse plane may be shifted medially or laterally from thecomponent-bisecting midline. This medial or lateral “shift” of thepatellar groove can be made independently of the medial or lateral cantof the patellar groove angle.

Advantageously, patellar grooves of femoral components made inaccordance with the present disclosure may provide enhanced articularcharacteristics, including minimized patient discomfort in the anteriorknee after knee arthroplasty, minimized risk of patella subluxationduring extension and flexion of the knee, and prolonged service life ofthe prosthetic femoral component and natural or prosthetic patella.

2. Definitions and Lexicon

Referring to FIG. 1, femoral component 10 resides within implantcoordinate system ICS including sagittal plane SP, transverse componentplane TP_(C) and coronal plane CP. For purposes of the presentdisclosure, implant coordinate system ICS is referenced to femur F (FIG.5) such that planes TP_(C), SP and CP may be considered fixed in theirrespective orientations and positions relative to femur F in the mannerdescribed below, irrespective of movements in other parts of a patient'sbody. Transverse plane TP_(C), coronal plane CP, and sagittal plane SPgenerally correspond to anatomic transverse, coronal and sagittal planesrespectively, but are not necessarily coplanar with same. The specificorientations of planes TP_(C), CP, SP are defined according to thediscussion herein.

Component transverse plane TP_(C) is tangent to the distal-most pointsof condyles 12, 14 of femoral component 10, and extends generallymediolaterally and anteroposteriorly. Transverse plane TP_(C) isperpendicular to anatomic axis AA of femur F when component 10 isproperly mounted to femur F (as described below). Moreover, thedistal-most points of condyles 12, 14, taken in the abstract, willgenerally correspond to the distal-most points of condyles 12, 14 withrespect to anatomic axis AA when femoral component 10 is mounted tofemur F.

While it is contemplated that a surgeon has some flexibility in themanner and method with which femoral component 10 is implanted ontofemur F, the actual distal-most points of condyles 12, 14 aftercomponent implantation will only vary slightly. For example, the surgeonis limited in making a posterior cut on femur F by the extent to whichnatural femoral condyles 3, 4 extend posteriorly past the femoralcortex, because the surgeon will traditionally seek to avoid resectionof any portion of the femoral shaft. An anterior cut is similarlylimited, and is typically nearly parallel to the posterior cut. Finallythe distal cut is typically performed to resect no more bone thannecessary. In view of these physical constraints on the resection offemur F, any variability in the actual distal-most points of condyles12, 14 arising from surgeon discretion during implantation of femoralcomponent 10 will have a negligible effect on the overall medial orlateral cant and/or shift. In the illustrated embodiment, transverseplane TP_(C) is parallel with bone-contacting surface 13 of component 10(FIGS. 1 and 2), though it is contemplated that surface 13 may have anyangular arrangement.

Moreover, a surgeon will recognize, with a high degree of certainty andprecision, which points on a prosthetic femoral component willcorrespond to the distal-most and posterior-most points afterimplantation. Taken in conjunction with a surgical technique proposed bymanufacturers of such components, the location of distal-most andposterior-most points on the component can be determined even moreexactly.

Coronal plane CP is generally perpendicular to transverse plane TP_(C)and sagittal plane SP, and is anteroposteriorly positioned to becoincident with at least one posterior-most point on condyles 12, 14 ofcomponent 10 (FIG. 2). Coronal plane CP is parallel to anatomic axis AA(described below) of femur F, as illustrated in FIG. 2. When component10 is properly mounted to femur F (as described below), coronal plane CPgenerally corresponds to the posterior-most points of the (formerlyunresected) natural condyles 3, 4 of femur F.

It is contemplated that coronal plane CP may be defined as an anatomiccoronal plane CP or a mechanical coronal plane CP. The anatomic coronalplane CP is tangent to both posterior-most points of condyles 3,4 in anatural knee, and is tangent to the posterior-most points of condyles12, 14 in a knee which has component 10 implanted. The anatomic plane istherefore inclusive of articular line L_(A) (FIG. 6A) when the knee isarticulated to a 90-degree flexion orientation. The mechanical coronalplane CP is tangent to only one of condyles 3, 4 (or condyles 12, 14)when the knee is flexed to 90-degrees, and is parallel to transversetibial plane TP_(T). As described below, transverse tibial plane TP_(T)is a transverse plane fixed with respect to tibia T and parallel tomechanical transverse plane TP_(M) when femur F is in the extensionposition.

Sagittal plane SP is generally perpendicular to transverse plane TP_(C)and is mediolaterally positioned to bisect condyles 12, 14. In theillustrated embodiment of FIGS. 3 and 4, sagittal plane SP forms midlineL_(M), which is equidistant from the edges of condyles 12, 14 and isnormal to component transverse plane TP_(C). When component 10 isproperly mounted to femur F (as described below), condyles 3, 4 are alsosubstantially bisected by sagittal plane SP, so that sagittal plane SPis generally coincident with the “top” or proximal-most point 5 ofpatello-femoral groove 6 (FIG. 5) of femur F, as viewed in coronal planeCP.

Referring now to FIG. 5, natural femur F defines mechanical axis MA andanatomical axis AA. Mechanical axis MA extends from the center offemoral head 7 to the center of the knee joint and is the weight bearingaxis of femur F. Anatomical axis AA extends along the longitudinal axisof shaft 8 of femur F. A surgeon may find anatomical axis AA by, e.g.,obtaining pre-operative images (such as CT scans, magnetic resonanceimagining, X-rays or the like) and estimating the longitudinal axis ofthe shaft of femur F based on sight and appearance. During a surgicalprocedure, a surgeon may find anatomical axis AA by inserting anintramedullary rod into the intramedullary canal of femur F. Once therod is so inserted, the axis of the rod is substantially coincident withthe axis of femur F. To find mechanical axis MA, a surgeon may again usepreoperative images to estimate the location of axis MA by sight.Alternatively, the surgeon may use a rod-based system in conjunctionwith manipulation of the leg to find axis MA. One exemplary rod-basedsystem and method for finding a mechanical femoral axis is described inU.S. patent application Ser. No. 12/695,804, filed Jan. 28, 2011 andentitled APPARATUS AND METHOD FOR THE EXTRAMEDULLARY LOCATION OF THEMECHANICAL AXIS OF A FEMUR, which is commonly assigned with the presentapplication, the entire disclosure of which is hereby expresslyincorporated herein by reference.

Once either mechanical axis MA or anatomical axis AA is determined, asurgeon may infer the location of the other by the knowledge that angleΘ (FIG. 5) separating axes MA, AA is typically about 6 degrees, asviewed in a coronal plane (e.g., the plane of FIG. 5).

Femur F defines two transverse planes, each of which is referenced todifferent anatomical structures defined by femur F. Mechanicaltransverse plane TP_(M) is normal to mechanical axis MA of femur F. Inthe illustrated embodiment, mechanical transverse plane TP_(M) iscoincident with distal-most point 2 of condyle 4, though other verticallocations are contemplated.

The other transverse plane of femur F is anatomic transverse planeTP_(A), which includes a line extending from distal-most point 1 oflateral condyle 3 to distal-most point 2 of medial condyle 4 and isperpendicular to coronal plane CP. As noted below, coronal plane CP isparallel to anatomic axis AA of femur F, so that anatomic transverseplane TP_(A) is perpendicular to anatomic axis AA from a sagittalperspective. Alternatively, anatomic transverse plane TP_(A) may bedefined as a plane tangent to distal-most points 1, 2 of condyles 3, 4.For the above methods of defining plane TP_(A), distal-most points 1, 2may be defined as the distal-most points on an undamaged femur F. In yetanother alternative, transverse plane TP_(A) may be defined as having afixed angle with mechanical transverse plane TP_(M), with the fixedangle chosen to render plane TP_(A) nearly tangent to distal-most points1, 2 for a statistically substantial portion of the patient population(i.e., based on analysis of empirical patient data).

In an exemplary embodiment, resection of femur F may leave a distalresected surface parallel to mechanical transverse plane TP_(M) tofacilitate a “mechanical orientation” of component 10 afterimplantation. Such a “mechanical” resection allows the use of a femoralcomponent with uniform thickness between distal bone-contacting surfaceand the articular surfaces of both medial condyle 12 and lateral condyle14. On the other hand, resection of femur F may leave a distal resectedsurface parallel to anatomic transverse plane TP_(A). Such “anatomic”resection facilitates an “anatomic orientation” of a component havingsimilarly constant condylar thickness. However, it is contemplated thatany resection may be used with a femoral component made in accordancewith the present disclosure, as required or desired for a particulardesign.

Referring still to FIG. 5, femur F defines anatomic varus/valgus angle αwithin the context of implant coordinate system ICS. For purposes of thepresent disclosure, anatomic varus/valgus angle α is the angle betweenmechanical transverse plane TP_(M) and anatomic transverse plane TP_(A).Angle α forms a basis for establishing and/or categorizing variationamong natural femurs, particularly within respective gender populations.The variation of anatomic varus/valgus angle α is a factor indetermining the degree of medialization or lateralization of patellarfemoral groove 16 in femoral component 10.

Turning back to FIGS. 1 and 2, femoral component 10 includes patellargroove 16, which defines patellar axis 18 (FIGS. 3 and 4) and patellarcurve 20 (FIG. 2). Patellar axis 18 and patellar curve 20 areprojections of a “valley line” formed along the “deepest” part of thevalley-like concavity formed by patellar groove 16, i.e., the lineformed by the points within patellar groove 16 that are furthest fromthe outside surface of component 10. This “valley line” is projectedonto coronal plane CP to create patellar axis 18, and onto sagittalplane SP to create patellar curve 20.

Referring to FIGS. 3 and 4, patellar axis 18 has a generally linearprofile, though it is contemplated that patellar axis 18 may benon-linear as required or desired for a particular design. Patellar axis18 may be medially or laterally canted and/or shifted, as discussed indetail herein, for particular applications. In an exemplary embodiment,described below, the location and orientation of patellar axis 18 may bevaried for gender- and/or ethnicity-specific applications.

Referring to FIG. 2, patellar curve 20 has a generally “J” shapeincluding distal-most point 22, which is the point having a minimumelevation E from component transverse plane TP_(C) to patellar curve 20when femoral component 10 is mounted to femur F. Distal-most point 22defines anteroposterior distance D_(A), which is the distance from point22 to the anterior-most point on femoral component 10. Similarly,distal-most point 22 defines anteroposterior distance D_(P), which isthe distance from point 22 to the posterior-most point on femoralcomponent 10 (i.e., coronal plane CP in the illustrated embodiment ofFIG. 2).

3. Femoral Component Construction

Referring again to FIG. 1, femoral component 10 includes medial condyle12, lateral condyle 14 and anterior flange 15. A plurality ofbone-contacting surfaces, including distal bone-contacting surface 13,are formed along the inner periphery of component 10. Disposed generallyopposite the bone-contacting surfaces, at the exterior periphery ofcomponent 10 are articular surfaces. For example, condyles 12, 14include distal and posterior articular surfaces for articulation with anatural tibia or prosthetic tibial component. These articular surfacescan have any geometry and shape as required or desired for a particularapplication.

Anterior flange 15 includes patellar groove 16, which forms the anteriorarticular surface of component 10 for articulation with a natural orprosthetic patella. Patellar groove 16 extends from a generally anteriorand proximal starting point to a generally posterior and distalterminus. Patellar groove 16 is adapted to articulate with a naturalpatella or prosthetic patellar component during the early stages of kneeflexion, after which the patella articulates with the inner surfaces ofcondyles 12, 14 near intercondylar fossa 24. For purposes of the presentdisclosure, the posterior and distal end of patellar groove 16 generallycoincides with the anterior terminus of intercondylar fossa 24 formedbetween medial and lateral condyles 12, 14. Because a natural orprosthetic patella articulates with the inner surfaces of condyles 12,14 in deep flexion, however, patellar groove 16 may be said to extendinto the distal portion of femoral component 10 near intercondylar fossa24.

In the illustrated embodiment, femoral component 10 further includesfixation pegs 26 and posterior cam 28 in accordance with a “posteriorstabilizing” femoral component design. However, it is contemplated thatthese structures may be eliminated or modified as required or desiredfor a particular application such as, for example, a “cruciateretaining” femoral component design with no posterior cam.

Femoral component 10 has several potential configurations to accommodateand account for natural variation among femurs of different patients.Such variations may arise from different bone sizes and geometries, andcorrespondingly different natural knee articulation characteristics,among patients of different gender, size, age, ethnicity, build or thelike. In addition, the configuration of femoral component 10, andparticularly of patellar groove 16, may be varied to account for and/orcorrect varus or valgus deformities in a particular patient.

As illustrated in FIG. 3, femoral component 10 includes patellar groove16 which may define either medially canted female patellar axis 18A ormedially canted male patellar axis 18B, depending on whether femoralcomponent 10 is configured for use with a male or female patient.Medially canted female patellar axis 18A defines angle β_(F) withrespect to component midline L_(M) (described above), while mediallycanted male patellar axis 18B defines angle β_(M) with respect tocomponent midline L_(M). As shown in FIG. 3 and described above, axes18A, 18B are “medially canted” in that they diverge medially fromcomponent midline L_(M) as these axes 18A, 18B extend proximally. Theembodiment of femoral component 10 illustrated in FIG. 3 is appropriatefor a “mechanical” component orientation, i.e., where componenttransverse plane TP_(C) is substantially parallel to and/or coincidentwith mechanical transverse plane TP_(M) (FIG. 5) after femoral component10 is implanted. In an exemplary embodiment of such a “mechanicalimplantation,” femur F may be prepared to receive femoral component 10by resecting at least the distal portions of natural condyles 3, 4 toform a resected surface substantially parallel to mechanical transverseplane TP_(M). However, it is contemplated that the resected surfaces offemur F may have any orientation relative to mechanical transverse planeTP_(M), with the bone-contacting surfaces of component 10 (such asdistal bone-contacting surface 13) adjusted to effect the desiredmechanical orientation of component 10 after implantation.

For a female patient with a mechanically oriented femoral component 10(FIG. 3, and as described above), femoral component 10 includes patellargroove 16 defining female medially canted patellar axis 18A formingangle β_(F) with component midline L_(M) in coronal plane CP. In anexemplary embodiment, angle β_(F) may be any angle between as little asabout 3° and as much as about 7°. In the illustrative embodiment of FIG.3, β_(F) is about 6.8°. Advantageously, a value of about 6.8° for angleβ_(F) provides an optimized patella/femur interaction between a naturalor prosthetic patella and patellar groove 16 for a large population offemale patients.

For a male patient with a mechanically oriented femoral component 10(FIG. 3), femoral component 10 includes patellar groove 16 defining malemedially canted patellar axis 18B, which forms angle β_(M) between malemedially canted patellar axis 18B and component midline L_(M). In anexemplary embodiment, angle β_(M) is generally smaller than thecorresponding angle β_(F) for a female patient, though male medial cantangle β_(M) may also be as little as about 3° and as much as about 7°.In the illustrative embodiment of FIG. 3, β_(M) is about 4.5°. Similarlyto the value of 6.8° for angle β_(F), a value of 4.5° for angle β_(M)provides an optimized patella/femur interaction between a natural orprosthetic patella and patellar groove 16 for a large population of malepatients.

Referring again to FIG. 4, for an anatomically oriented femoralcomponent 10, male and female components made in accordance with thepresent disclosure may have the same patellar axis/mechanical axisangle. In FIG. 4, femoral component 10 is configured to be implanted onto femur F in an anatomic orientation (i.e., “anatomically implanted”),and includes patellar groove 16 defining laterally canted patellar axis18C. Laterally canted patellar axis 18C is angled such that axis 18Cdiverges laterally from component midline L_(M) as axis 18C extendsproximally.

A gender-neutral or “universal” angle β_(U) may be formed betweenlaterally canted patellar axis 18C and component midline L_(M) whenfemoral component 10 is configured for an anatomic implantation. Theuniversality of angle β_(U) is made possible because a desirablearticulation profile between a natural or prosthetic patella andpatellar groove 16 of femoral component 10 has been found to berelatively angle-independent for both male and female patients. Moreparticularly, the optimal angle between axis 18 and mechanical axis MAis only slightly variable for males versus females (as discussed indetail below), with the variation being small enough to enable femoralcomponent 10 to have the same laterally canted patellar axis for bothmale and female components without compromising the fit, function orother advantages conferred by pairing laterally canted patellar axis 18Cof femoral component 10 with an anatomical orientation upon implantationof component 10. In an exemplary embodiment, β_(U) may be as little as0° (i.e., patellar groove 16 defines a patellar axis 18C that isparallel to, or coincident with, component midline L_(M)) and as much as4°, for example. In the illustrative embodiment of FIG. 4, β_(U) isabout 2°.

The gender neutrality of component 10 with a laterally canted patellargroove 16 is related to anatomic varus/valgus angle α. As discussedabove, angle α is the angular disparity between mechanical transverseplane TP_(M) and anatomic transverse plane TP_(A), and is measured in anextension orientation of the knee. Thus, referring to FIG. 5, angle αcan be thought of as the angle between a line tangent to the articularsurfaces of condyles 3, 4 (which, in extension, are also distal-mostpoints 1, 2) and mechanical transverse plane TP_(M).

However, α is also a relevant angular value throughout flexion of theknee when component 10 is mounted to femur F in an anatomic orientation.Referring now to FIGS. 6 and 6A, articular line L_(A) forms angle α withtransverse tibial plane TP_(T), which is a transverse plane fixed totibia T and parallel to mechanical transverse plane TP_(M) when femur Fis in the extension position. Articular line L_(A) is tangent to thearticular surfaces of condyles 12, 14 at the articular interface betweencomponent 10 and tibia T (or a tibial component, not shown) at a givendegree of flexion. In extension, articular line L_(A) is coincident withcomponent transverse plane TP_(C), as shown in FIG. 6A. As the kneeflexes, articular line L_(A) shifts posteriorly along the articularsurfaces of condyles 12, 14. As shown in FIG. 6B, for example, articularline L_(A) has shifted to the posterior-most points of femoral component10 as the knee has flexed to approximately 90 degrees. However, theangle between articular line L_(A) and transverse tibial plane TP_(T)remains unchanged (i.e., equal to angle α). This lack of angular changethroughout flexion has been found to mimic articulation characteristicsof the natural knee. Moreover, the anatomic implantation of femoralcomponent 10 cooperates with the slight lateral cant of patellar axis18C to render component 10 gender neutral.

In view of the general concept underlying the present disclosure and asexplained above, it may be noted that the anatomic varus/valgus angle αis at least roughly related to certain values of the cant angles asdisclosed herein and which have found to be advantageous. Specifically,it has been found that the average sum of an advantageous medial cantangle (e.g. approximately between 3 degrees and 7 degrees) and anadvantageous lateral cant angle (e.g. approximately between zero degreesand 4 degrees) corresponds roughly to an anatomic varus/valgus angle α.Exemplary embodiments of femoral component 10 include medially orlaterally canted patellar grooves 18A, 18B, 18C which correspond to onesuch average sum equal to about 7 degrees. These exemplary componentsrepresent an ideal prosthesis/anatomy match that is expected tocorrespond to the largest possible proportion of anatomic structuresfound among patient populations.

Referring back to FIG. 2, patellar curve 20 includes distal-most point22 defining elevation E between component transverse plane TP_(C) anddistal-most point 22. In addition, distance D_(A) is defined betweendistal-most point 22 and the anterior face of anterior flange 15, whileposterior distance D_(P) is defined between distal-most point 22 and theposterior face of medial and/or lateral condyles 12, 14.

It is contemplated that other characteristics of femoral component 10may vary depending on whether femoral component 10 is adapted for ananatomic or mechanical implantation. For example, it is contemplatedthat elevation E may be smaller for femoral component 10 adapted foranatomic implantation (FIG. 4) as compared to femoral component 10adapted for mechanical implantation (FIG. 3). Further, anterior flange15 of femoral components 10 adapted for anatomic implantation may beless high and less broad, i.e. generally smaller, when viewed from ananterior side (as in FIGS. 3 and 4), as compared to femoral componentsadapted for mechanical implantation.

In addition to the medial or lateral cant of patellar axis 18 (which maybe one of patellar axes 18A, 18B and 18C, as noted above), patellar axis18 may also be medially or laterally shifted or “translated” on anteriorflange 15 of femoral component 10. For example, referring to FIG. 3,male medially canted patellar axis 18B defines lateral shift distanceD_(L), which is the distance, as measured in coronal plane CP, betweencomponent midline L_(M) and the point where medially canted axis 18Bintersects component transverse plane TP_(C). In an exemplaryembodiment, lateral shift distance D_(L) may be between 0 and about 4mm, for example, depending upon the desired location of axis 18B and onthe particular characteristics of femoral component 10, such as implantsize, implant thickness, and the like. Although lateral shift distanceD_(L) is illustrated with respect to male medially canted patellar axis18B of femoral component 10, it is contemplated that otherconfigurations of femoral component 10 may have other configurations ofpatellar axis 18 that are laterally shifted to define lateral shiftdistance D_(L), i.e., medially canted patellar axis 18A or laterallycanted patellar axis 18C.

On the other hand, the illustrative embodiment of FIG. 4 includeslaterally canted patellar axis 18C defining medial shift distance D_(M),which is the distance, as measured in coronal plane CP, betweencomponent midline L_(M) and the point where laterally canted axis 18Cintersects anatomic transverse plane TP_(A). In an exemplary embodiment,medial shift distance D_(M) may be between 0 mm and about 4 mm, forexample, depending upon the desired location of axis 18C and on theparticular characteristics of femoral component 10 such as implant size,implant thickness, and the like. Similar to lateral shift distanceD_(L), medial shift distance D_(M) may be defined by any of mediallycanted or laterally canted patellar axes 18A, 18B, or 18C.

Although femoral component 10 is described above as being a singlecomponent having several varying configurations, it is contemplated thata set or kit of femoral components 10 may be provided for use in eithera mechanical or anatomic orientation of component 10 after implantationthereof. Each kit may include a plurality of implant sizes for variousdifferent sizes of femur F, as may be encountered in various individualpatients. In the case of femoral component 10 adapted for use in amechanical implantation, a first full set or kit may be provided forfemale patients, while a second full set or kit may be provided for malepatients. These two gender-specific kits are provided because femoralcomponent 10 is configured differently for male and female patients whenmechanically oriented (i.e., femoral component 10 includes either malemedially canted patellar axis 18A or female medially canted patellaraxis 18B, as shown in FIG. 3 and discussed above).

On the other hand, where femoral component 10 has lateralized patellaraxis 18C adapted for use in an anatomic implantation, a single kit maybe provided for both male and female patients. This single,gender-neutral kit of anatomically oriented components will generallyinclude a larger number of components as compared to a gender-specifickit of mechanically-oriented component, because the gender-neutral kitwill include a wider range of component sizes to accommodate the sizedisparities between male and female femur populations.

Advantageously, femoral components made in accordance with the presentdisclosure may be provided as kits or sets which are gender specific,particularly where a mechanical implantation is intended, while alsointegrating any number of other technologies and features now known orlater discovered. Moreover, a patellar groove in accordance with thepresent disclosure may be integrated into a wide range of other existingfemoral component designs, such that the components offer the benefitsof a medially canted or laterally canted patellar groove 16 as describedabove, while also providing other unique features, articularcharacteristics and/or kinematic profiles. Thus, the patello-femoralbenefits and advantages, discussed above, may be obtained for a widevariety of patient populations while also benefitting from otherorthopaedic technologies such as particular condyle designs, componentaffixation designs and methods, advanced materials, and the like.

Also advantageously, femoral components 10 are adapted to be implantedin mechanical and anatomic orientations, respectively, to substantiallyreproduce or mimic the natural kinematic profile of healthyfemur/patella interaction in a natural knee. As described below,analysis of healthy patient patellar grooves and other characteristicsof healthy patient femurs confirms that a medially canted patellar axis,used in conjunction with a mechanical implantation of femoral component10, can be used to achieve enhanced articular characteristics (such as,for example, patello-femoral articular characteristics) in a kneeprosthesis. Similarly, this analysis further confirms that enhancedarticular characteristics can be gained from the use of femoralcomponents having a laterally canted patellar axis in conjunction withan anatomic implantation of femoral component 10. In each case, femoralcomponents made in accordance with the present disclosure have beenfound to produce desirable articular characteristics while using apatellar groove that is canted and/or oriented in a manner contrary toconventional wisdom in the art of orthopaedic femoral prostheses.

Advantageously, the enhanced patello-femoral joint articulation providedby femoral component 10 may include, among other benefits: minimizedanterior knee pain following a TKA procedure; maintenance of appropriatetension in the retinaculum, thereby minimizing risk to same duringsurgical procedures; promotion of appropriate/optimum intraoperativesurgical decisions regarding the relative size and geometry of thelateral femoral condyle; minimization or elimination of externalrotation of the femoral component with respect to the femur; minimizedrisk of patella subluxation during articulation of the knee prosthesis,particularly at extreme extension and extreme flexion ranges of motion;and greater longevity of components in the knee prosthesis, such asfemoral component 10, a natural or prosthetic patella and/or a tibialcomponent, for example.

Yet another advantage of femoral component 10 in accordance with thepresent disclosure is that the articulation between a natural orprosthetic patella and patellar groove of femoral component 10facilitates femoral lateral rollback in deep flexion.

A procedure to mount femoral components 10 with medially canted patellaraxes 18A or 18B to femur F will now be described. Prior to resection offemur F, the alignment and orientation of mechanical axis MA andanatomical axis AA for femur F is determined and noted. A resection isperformed using conventional methods and instruments. In an exemplaryembodiment, the resection creates a distal cut surface normal tomechanical axis MA (and, concomitantly, parallel to mechanicaltransverse plane TP_(M)), though other cut geometries may be used.Corresponding anterior, posterior, anterior chamfer and/or posteriorchamfer cuts are also made as necessary.

The surgeon then provides femoral component 10 for implantation ontofemur F. As used herein, “providing” femoral component 10 refers toprocurement thereof, such as from a kit or operating-room container orstorage receptacle. Prior to the step of providing component 10, thesurgeon may or may not be involved with acquisition from themanufacturer, receipt of shipments, inventorying, or other procurementactivities occurring outside the operating room environment.

Femoral component 10 having one of medialized groove 18A or 18B(depending on the gender of the patient, as described herein) is thenmounted to femur F so that component transverse plane TP_(C) is parallelto and/or coincident with mechanical transverse plane TP_(M). Thefixation of femoral component 10 to femur F is accomplished usingconventional fixation methods and structures, such as bone cement,bone-ingrowth material and/or fixation pegs 26, for example. Aprosthetic patellar component may also be implanted to cooperate withfemoral component 10, or the natural patella may be retained for sucharticulation. Range of motion may be analyzed, including observation andanalysis of patello-femoral kinematic and articular characteristics.When the surgeon is satisfied with the location and placement of femoralcomponent 10 and any other associated components of the knee prosthesis,surgery is completed in accordance with conventional methods.

The procedure to mount femoral components 10 with laterally cantedpatellar axes 18C to femur F is similar to the corresponding procedurefor components 10 with medially canted patellar axes 18A, 18B describedabove. However, rather than selecting component 10 with medially cantedaxes 18A, 18B and implanting such component 10 so that componenttransverse plane TP_(C) is parallel to and/or coincident with mechanicaltransverse plane TP_(M), component 10 is selected with laterally cantedpatellar axis 18C and is implanted such that component transverse planeTP_(C) is parallel to and/or coincident with anatomic transverse planeTP_(A), as described above.

While this invention has been described as having an exemplary design,the present invention can be further modified within the spirit andscope of this disclosure. This application is therefore intended tocover any variations, uses, or adaptations of the invention using itsgeneral principles. Further, this application is intended to cover suchdepartures from the present disclosure as come within known or customarypractice in the art to which this invention pertains and which fallwithin the limits of the appended claims.

What is claimed is:
 1. A femoral component adapted to mount to a femur,the femur defining a mechanical axis and an anatomic axis, the componentdefining a component coordinate system having: a component transverseplane; a coronal plane perpendicular to said component transverse plane;a sagittal plane perpendicular to said component transverse plane andincluding a component midline that is normal to said componenttransverse plane; the component having a bone-contacting surface and anopposed articulation surface, the component further having proximal,distal, anterior and posterior portions, the component comprising: apair of condyles including a medial condyle and a lateral condyle, eachof said condyles defining respective distal-most points andposterior-most points, said component transverse plane tangent to eachof said distal-most points, said coronal plane tangent to at least oneof said posterior-most points, and said sagittal plane disposed betweensaid lateral condyle and said medial condyle; and a patellar grooveproximate the anterior portion of the component, said component midlineof said sagittal plane inclusive of a distal-most point of said patellargroove, said patellar groove extending from said distal-most pointtoward an anterior-most edge of said femoral component, said patellargroove defining a medially canted patellar axis when viewed from ananterior side of said component, said patellar axis medially divergingfrom said component midline as said patellar axis extends proximally todefine a medially canted angle between said patellar axis and saidcomponent midline.
 2. The femoral component of claim 1, wherein saidmedially canted angle comprises an angle between about 3 degrees andabout 7 degrees.
 3. The femoral component of claim 1, wherein saidfemoral component comprises a femoral component sized and shaped for amale patient, and said medially canted angle comprises an angle that isabout 4.5 degrees.
 4. The femoral component of claim 1, wherein saidfemoral component comprises a femoral component sized and shaped for afemale patient, and said medially canted angle comprises an angle thatis about 6.8 degrees.
 5. The femoral component of claim 1, wherein saidcomponent midline and said patellar axis intersect the componenttransverse plane at a common point.
 6. The femoral component of claim 1,wherein said component midline and said patellar axis intersect thecomponent transverse plane at a pair of different points spaced from oneanother by a mediolateral distance, in particular said mediolateraldistance between zero mm and 4 mm.
 7. The femoral component of claim 1,wherein said patellar axis extends straight from said distal-most pointto said anterior-most edge of said femoral component.
 8. The femoralcomponent of claim 1, wherein said component transverse plane issubstantially perpendicular to said femur mechanical axis.
 9. A set offemoral components adapted to mount to a femur having an anatomic axisand a mechanical axis, the femur having lateral and medial condyles withrespective distal-most points before resection, the femur defining amechanical transverse plane normal to the mechanical axis and ananatomic transverse plane tangent to each of said distal-most points,the set comprising: a first femoral component having a first lateralcondyle, a first medial condyle opposite said first lateral condyle,such that a path from said first lateral condyle toward said firstmedial condyle defines a medial direction, and a first anterior flangejoining said first lateral condyle to said first medial condyle, saidfirst anterior flange having a patellar groove defining a mediallycanted patellar axis extending in said medial direction as said mediallycanted patellar groove extends proximally; and a second femoralcomponent having a second lateral condyle, a second medial condyleopposite said second lateral condyle, such that a path from said secondmedial condyle toward said second lateral condyle defines a lateraldirection, and a second anterior flange joining said second lateralcondyle to said second medial condyle, said second anterior flangehaving a patellar groove defining a laterally canted patellar axisextending in said lateral direction as said laterally canted patellargroove extends proximally, said first lateral and medial condyles andsaid second lateral and medial condyles each defining respectivedistal-most points and respective posterior-most points, each of saidfirst femoral component and said second femoral component defining acomponent coordinate system having: a component transverse plane tangentto each of said distal-most points; a coronal plane perpendicular tosaid component transverse plane and tangent to at least one of saidposterior-most points; and a sagittal plane perpendicular to saidcomponent transverse plane and disposed between said first lateralcondyle and said first medial condyle, said sagittal plane inclusive ofa distal-most point of said patellar groove, said sagittal planeincluding a component midline that is normal to said componenttransverse plane and inclusive of said distal-most point of saidpatellar groove, said medially canted patellar axis of said mediallycanted patellar groove of said first anterior flange defining a mediallycanted angle with respect to said component midline, when viewed from ananterior side of said first femoral component, and said laterally cantedpatellar axis of said laterally canted patellar groove of said secondanterior flange defining a laterally canted angle with respect to saidcomponent midline, when viewed from an anterior side of said secondfemoral component.
 10. The femoral component of claim 9, wherein saidmedially canted angle comprises an angle between about 3 degrees andabout 7 degrees.
 11. The femoral component of claim 9, wherein saidfirst femoral component comprises a femoral component sized and shapedfor a male patient, and said medially canted angle comprises an anglethat is about 4.5 degrees.
 12. The femoral component of claim 9, whereinsaid first femoral component comprises a femoral component sized andshaped for a female patient, and said medially canted angle comprises anangle that is about 6.8 degrees.
 13. The femoral component of claim 9,wherein said second femoral component is one of a male and femalefemoral component, and said laterally canted angle is about 2 degrees.14. The femoral component of claim 9, wherein said second femoralcomponent comprises a gender-neutral femoral component.
 15. The femoralcomponent of claim 9, wherein: said medially canted patellar groove ofsaid first anterior flange extends from said distal-most point of saidpatellar groove straight toward an anterior-most edge of said firstfemoral component; and said laterally canted patellar groove of saidsecond anterior flange extends from said distal-most point of saidpatellar groove straight toward an anterior-most edge of said secondfemoral component.
 16. The femoral component of claim 9, wherein: saidcomponent transverse plane of said first femoral component issubstantially perpendicular to said femur mechanical axis; and saidcomponent transverse plane of said second femoral component issubstantially perpendicular to said femur anatomical axis.